The present invention relates to a process for preparing substantially spheroidal alumina particles. The present invention also relates to a process for preparing catalysts from these spheroidal alumina particles.
Metallic oxides, and particularly alumina, are widely used in the chemical industry, typically as catalysts, catalyst supports, absorbing agents, etc. For the most of these applications, these oxides preferably are used in the form of spheroidal particles or beads. Among the main advantages of these particles are better wear and crushing strength. These particles may be more regular distributed into the reactors, thereby reducing the pressure drop variations of the reactants passing through the reactors.
Several processes have been proposed for preparing spheriodal alumina particles. One of such processes includes dispersing an alumina hydrosol as droplets in a medium where gelation occurs, and thereafter, subjecting the resulting beads which are obtained in the form of alumina hydrogel, to one or more aging treatments in order to obtain beads having a suitable mechanical resistance. According to another known process, an alumina hydrosol is mixed with an ammonium salt and a synthetic polymer or a natural gum and the resulting mixture dispersed into a water-immiscible medium and thereafter subjecting to an aging treatment. However, these processes have the disadvantage of requiring very long treatment times which render them uneconomic. Moreover, alumina beads prepared by some of these known processes contain high amounts, even excessive amounts on occasion, of impurities which are undesirable when these beads are used as catalysts or catalyst supports.
An object of the present invention is to provide a new and improved method for preparing spheroidal alumina particles.
A further object of the present invention is the preparation of particles whose catalytic activity is not inhibited by impurities.
Still another object of the present invention is to provide a new and improved process for preparing particles having a uniform size.
A remaining object of the present invention is to provide a process which allows the preparation of smooth surfaced alumina beads having a high resistance to crushing. Additional objects will become apparent from the following description of the invention herein disclosed.